Effectively regulating interfacial polymerization process via in-situ constructed 2D COFs interlayer for fabricating organic solvent nanofiltration membranes

Covalent organic frameworks (COFs) nanomaterials have broad application prospects for the fabrication of separation membranes due to their high porosity, adjusted pore size, and excellent chemical stability. In this work, we in-situ constructed an ultra-thin layer of two-dimensional COFs nanomaterial using interfacial condensation between p-phenylenediamine and 1,3,5-triformylphloroglucinol, both with ultra-low concentration, on polyimide substrate surface to manipulate the subsequent interfacial polymerization between m-phenylenediamine of ultra-low concentration and trimesoyl chloride to fabricate a kind of thin film nanocomposite (TFN) membrane for organic solvent nanofiltration (OSN). The fabricated TFN OSN membrane achieves a Rhodamine B (479 Dalton) rejection and an ethanol permeance of higher than 99% and of 60 L m−2 h−1 MPa−1, respectively. Moreover, it has ultra-smooth surface with much thin skin layer, and high permeance for polar solvents such as methanol and ethanol. Besides, it has a molecular weight cut-off of about 375 Dalton. Moreover, it can maintain good separation performance after more than 10 days' immersion in N, N-dimethylformamide (DMF) at 80 °C, or after 120 h crossflow filtration with 100 mg L−1 Rose Bengal (1017 Dalton) - DMF solution as feed at 25 °C, indicating its vast potential for industrial application in harsh solvent environment.